CCS: How much time does asm(" NOP ") use ?

Ronnie

Tool/software: Code Composer Studio

asm(" NOP ") instruction can be used for delay, so how much time does asm(" NOP ") use in F2806x DSP chip of which the clock frequency is 90Mhz?

over 8 years ago

0 Archaeologist over 8 years ago

TI__Guru* 84285 points

As a rule, it takes one CPU cycle, so if you are running at 90 million cycles per second, it'll consume approximately 1/90e6 seconds.

However, you really shouldn't use NOP delays for anything but the very smallest delays. You'll be better off setting a timer and going into a low-power mode.

0 Ronnie over 8 years ago in reply to Archaeologist

Intellectual 750 points

But debugging through breakpoint in CCS, it shows asm(" NOP ") instruction occupies 393 clock events, but not 1/90e6 seconds.

0 Archaeologist over 8 years ago in reply to Ronnie

TI__Guru* 84285 points

Well, there could be many reasons for that. Are you sure it's the NOP consuming the time, and not a nearby memory access? Also, stepping through the code with the debugger can alter the timing behavior.

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CCS: How much time does asm(" NOP ") use ?